Conventionally, various forms of electroconductive contact units have been used in contact probes for conducting electric tests on electroconductive patterns of printed circuit boards and electronic component parts (open/short tests, environment tests and burn-in tests), sockets (including packages) for semiconductor devices (LGA, BGA, CSP and bare chip), and connectors.
When using such a socket for semiconductor devices, it is necessary to consider the fact that signal frequencies for semiconductor devices have significantly increased in recent years, and may be as high as hundreds of MHz. A socket for semiconductor devices that operate at such a high frequency level is required to use electroconductive contact units of low inductance and resistance and to be of a highly compact design in terms of mounting space.